Optical alignment in capillary detection using capillary wall scatter

Abstract

The present invention provides for methods and apparatus for locating a capillary channel that is disposed within a lab chip. The method provides for scanning the channel with a light source, monitoring the resulting light at the edges of the lab chip, and interpreting this information whereby the light detected at the edges of the lab chip can be used as a means for characterizing the location of the side walls of the channel within the lab chip. The apparatus provides for a carriage system to which a light source and the lab chip are attached. It also provides for one or more scatter detectors directed towards the edges of the chip and connected to a computer processor for purposes of analysis.

What is claimed is:  
     
       1. A method for determining the location of a sloped side wall of a microchannel disposed in a light transmitting substrate, said method comprising: 
       scanning a portion of said substrate with a light source in a direction that is angled with respect to the direction of channel flow, said portion including said side wall of said microchannel;  
       monitoring the relative movement between said substrate and said light source during said scanning while measuring light emanating from at least one edge of said substrate;  
       correlating said emanating light to the relative positions between said light source and said substrate during said scanning, and  
       determining the location of said side wall within said substrate from said correlating.  
     
     
       2. The method of  claim 1 , wherein the substrate is comprised of a laminate having at least two layers. 
     
     
       3. The method of  claim 2 , wherein where said layers have the same refraction indices. 
     
     
       4. The method of  claim 2 , wherein said layers have different refraction indices. 
     
     
       5. The method of  claim 1 , for use in detecting fluorescent sample components moving within said channel, by irradiating a region of the channel with a focused laser beam and detecting light emitted from the channel, wherein said beam is placed a selected lateral distance from the determined location of said side wall. 
     
     
       6. The method of  claim 5 , wherein said selected lateral distance is determined from the lateral distance in the microchannel between the determined location of a microchannel side wall and the lateral position of said beam within the channel that gives a maximum fluorescence signal. 
     
     
       7. The method of  claim 5 , wherein said selected lateral distance is determined as the midpoint in the channel between the determined location of the microchannel side wall and the determined location of the opposite channel side wall. 
     
     
       8. The method of  claim 5 , wherein said substrate has a plurality of microchannel units, the selected lateral distance is determined for one of the units, and applied to the other units when detecting fluorescent sample components moving within channels of such other units.